Many driven devices, such as bicycles, motorcycles, motor vehicles, etc., require the use of a transmission assembly in order to translate driving forces to drive the driven device. Typically, these transmission assemblies allow the adjustment of the final drive ratios of these devices to optimize the translation of input power to the driven device.
For example, chain and sprocket with a deraileur assembly have been used and implemented on conventional bicycles. One problem with the chain and sprocket type assembly is that the gears are discrete. Also, the chain at times becomes misaligned from the sprocket and/or deraileur assembly causing inconvenience and possible injury to the cyclist. Furthermore, this type of assembly requires the cyclist to pedal in order to shift gears. Additionally, the use of chains to sprockets/gears does not allow for a smooth continuous transition between drive ratios.
Therefore, various transmission assemblies have been developed in attempting to overcome some of the above limitations of the chain, sprocket, and derailleur type transmission assembly. For example, transmission assemblies have been developed to provide infinitely variable drive ratios within a range to overcome having to only provide discrete gears/drive ratios. U.S. Pat. Nos. 3,889,974; 3,922,005; 3,954,282; 3,984,129; 4,271,712; 4,467,668; 4,574,649; 4,630,839 disclose examples of such infinitely variable drive ratio transmission assemblies, and these prior art patents are incorporated by reference herein. These transmission assemblies use cables and chains and various other components that act in a reciprocating manner. However, a problem with the transmission assemblies is that they require an up and down type motion or back and forth type motion of the pedals or driving devices. A user of these transmission assemblies find these types of motions unsatisfactory since they are more accustomed to a fluid circular driving motion of the pedals/driving devices. Therefore, the use of these transmission assemblies may provide discomfort to the user.
Thus, transmission assemblies that allow adjustment of the pedal arm lengths were developed. U.S. Pat. Nos. 4,706,516; 4,519,271; 5,095,772 disclose examples of such transmission assemblies, and these prior art patents are incorporated by reference herein. These transmission assemblies provided a circular driving motion for the user. However, these types of transmission assemblies still did not provide a very fluid or comfortable motion for the user since the user would have to extend or retract his/her legs or pedaling motions respectively according to the adjustment of the transmission assemblies.
Therefore, transmission assemblies that provide infinitely variable drive ratios within a range, that implement reciprocating components, and that provide a circular driving motion for the user were developed. U.S. Pat. Nos. 4,133,550 and 5,833,257 disclose specific examples of such transmission assemblies, and these prior art patents are incorporated by reference herein. However, the need and desire to develop and improve these types of transmission assemblies and provide new apparatuses and methods to implement such transmission assemblies continues to exist.
Therefore, the present invention discloses and provides an adjustable rotational transmission assembly, and the present invention overcomes the problems, disadvantages, and limitations of the prior art.